1. Field of the Invention
This invention relates generally to sensor devices, and more particularly to a sensor device and method for monitoring physical stresses placed on a user, such as during physical rehabilitation exercises and the like, and alerting the user if the physical stresses exceed predetermined threshold force levels.
2. Description of Related Art
Beebe et al., U.S. Pat. No. 7,277,021, teaches a device for determining the wear of a sole of a shoe, to determine when the shoe is worn out and needs to be replaced. The device includes first and second sensors receivable in the sole of the shoe. The sensors are axially spaced and generate signals in response to corresponding impact forces acting thereon. A control circuit connectable to the first and second sensors compares the difference between the first and second signals to a threshold and generates an alert signal in response to the difference between the first and second signal meeting the threshold, thereby indicating that the shoe needs to be replaced, at which point an LED is illuminated. A similar device is shown in Hirsch et al., U.S. Pat. No. 6,578,291, which teaches a shoe having a built-in, electronic wear indicator device. The device includes an accelerometer for measuring foot movement.
Damen et al., U.S. Pat. No. 6,356,856, teaches a system built into a shoe or measuring the speed of a person while running or walking. An acceleration sensor measures the acceleration in the forward direction and provides an acceleration signal which is amplified and subsequently sampled by analog to digital converter. The digital signal is processed by a microprocessor which executes an algorithm that determines the stride length and the stride duration from the digitized acceleration signal and calculates the speed and the distance traversed. The information thus obtained is transmitted by an RF transceiver to a watch or other device which includes a display which can be viewed by the runner or walker. The speed and distance traversed is displayed on the display, along with other useful information, such as average speed, maximum speed, total distance traversed, calories expended, and heart beat.
Similar shoes are also shown in Huang, U.S. Pat. No. 5,875,571, Huang, U.S. Pat. No. 5,815,954, Hutchings, U.S. Pat. No. 5,724,265, and Huang, U.S. Pat. No. 5,661,916.
Cherdak, U.S. Pat. No. 5,452,269, teaches an athletic shoe which includes a timing device for measuring the amount of time the athletic shoe is off the ground and in air. The athletic shoe includes a notification device which can be operatively coupled to the timing device for notifying a wearer of the amount of time the athletic shoe is off the ground and in the air.
Wood, U.S. Pat. No. 5,373,651, teaches footwear adapted to measure the number and the force of steps that have been taken by the user during a predetermined interval. The wearer can subsequently transfer the step information into a computer for further analysis via an inductively coupled data link between the footwear and the computer.
Adams et al., U.S. 2007/0049853, teaches a compression device for a limb of a patient for applying a predetermined amount of pressure to the limb, and for reporting the pressure actually applied to the limb via an external reporting device. The compression device includes an inflatable sleeve arranged to surround the limb, and a conduit attached to the sleeve arranged to deliver fluid to the sleeve for providing the pressure. A control system controls fluid flow in the device and a memory arranged to store gathered data relating to use of the device.
The above-described references are hereby incorporated by reference in full.